Data Backup / Transfer method?

[Kuuribro]

Hello!
I am not sure where or how is the best way to ask, but I wanted to know if there is a known method for transferring data from one android device to another. I have gathered a handful of ebooks and dictionaries on one phone, and now I have a new phone and would like to copy things over.
I know it is bad practice but I have lost track of the original source files I had for these dictionaries. I have the original books but it is very inconvenient to access them.

I found a backup option inside the app, but it requests a GDrive or Onedrive "Client ID" "Client Secret" and Password. I don't clearly understand what any of these are, and trying to create one had left me at a dead end asking for a password I never had to make either.

Is this even possible right now?